Theoretical Study on Traction Drives

The authors introduce a new type of drives--traction drives,and summarizethe present situation of theoretical study on traction drives.     

Analysis on Oylindrical Worm in Traction Machine and Modifications

Cone enveloping cylindrical worm in traction machine as instance, theoretical analysis on cylindrical worm transmission has been theoretically analyzed, and efficiency test and load capability test of traction machine with YJ240 cylindrical worm have been done on open power gear experimental instrument. According to the experimental data, it indicates cylindrical worm have some weaknesses on load capability, efficiency, adjustment possibility of tooth backlash and so on. Therefore, on purpose of improving integral performance of traction machine, face worm with variable tooth thickness may be used as primary drive mechanism in traction machine instead of cylindrical worm.     

Wear rate of animal-drawn ploughshares in selected Ghanaian soils

Rapid ploughshare wear was identified as a major constraint facing animal traction farmers in Ghana. The objectives of this study were to: (i) identify the types of animal-drawn ploughshare used by farmers and their production methods, (ii) develop and test a new cast steel share and compare its performance with existing ploughshares, and (iii) determine the factors responsible for the rapid wear and durability of ploughshares in selected soils in the country. To address this problem, new and used ploughshares were collected from farmers, blacksmiths and foundries and their microstructure, chemical composition and hardness were studied. Based on the above studies, new cast steel ploughshares were developed. On-farm tests were conducted on the new shares for wear and durability in the major animal traction soils in the country. On-station field trials with tractor-drawn shares were carried out to compare the performance of the new ploughshares with the imported and local blacksmith versions. Multivariate statistical methods were used to analyse the similarities among the shares with respect to producers, chemical composition, share hardness, soil physical factors (moisture content, bulk density, cone index and soil texture) and their relationship to wear rate. When pulled by tractor, the average wear rates of the imported, improved and blacksmith shares in soils containing 50%, 64% and 74% sand were 297, 362 and 562 g/ha, respectively. The average wear rates of the new share when pulled by animals in the major soil classifications were: Eutric Plinthosols, 146 g/ha; Plinthic Lixisols, 164 g/ha and Haplic Lixisols, 176 g/ha, respectively. This gave an average durability of 3–8 ha/share before the farmer declares the new ploughshare completely worn. This compares with 1–2 ha and 2–5 ha per share wear rates for the blacksmith-forged and the imported shares, respectively. The study concluded the new cast steel ploughshares have qualities of enhanced durability and toughness similar to the imported versions and more durable than the local blacksmith shares and have prospects for mass production.     

山地果园拆装牵引式双轨运输机控制系统的设计

【目的】设计适用于山地果园牵引式双轨运输机的控制系统,为山地果园牵引式运输机械的设计提供支持。【方法】在分析该类拆装牵引式双轨运输机整机结构及应用工况的基础上,针对山地果园拆装牵引式双轨运输机拆装频繁、应用环境恶劣等工况,运用控制系统硬件、软件设计理论与性能试验相结合的方法,设计一种以PLC为控制核心、液晶触摸屏为人机交互窗口的控制系统,重点分析控制系统的工作原理、硬件设计、软件设计、无线遥控设计和抗干扰措施,并对控制系统的核心部件及稳定性进行理论和试验研究。【结果】所设计的山地果园拆装牵引式双轨运输机控制系统运行可靠,定位系统的平均距离偏差为5.18cm,平均定位距离误差率为0.96%,平均脉冲误差率为0.68%;在有遮挡的情况下,无线遥控器在距离遥控接收装置300m范围内的通信成功率为100%。【结论】所设计的控制系统可满足运输机的智能化控制需求,该控制系统亦适用于其他钢丝绳提升式运输机的作业控制。     

卷盘式喷灌机牵引装置油光互补供电系统配置优化

针对卷盘式喷灌机灌溉准备工作中拖拉机牵引喷头车及供水管时存在的压实土壤、破坏作物、能耗浪费及灵活性差等问题,基于光伏板、蓄电池、汽油发电机互补供电技术,提出了一种电动牵引装置。根据牵引装置动力需求,以供电系统年费用为目标函数,以负载亏电率、蓄电池荷电状态为约束条件,以光伏板、蓄电池数目和汽油发电机额定功率为决策变量建立优化模型,利用基于罚函数的粒子群算法(Particle swarm optimization algorithm,PSO)求解,并在陕西省杨凌地区气候条件下进行了优化模型应用,得到年费用最低的供电系统配置:光伏板数目为2块、蓄电池数目为4块、汽油发电机额定功率为3 k W,此配置下年费用为2 740. 69元。通过不同配置方案的对比,对模型优化结果进行了验证。最后,以最优方案配置供电系统进行了为期3 d的田间运行试验,结果表明:不同时段、不同天气类型下系统发电量始终大于耗电量,系统累计发电量为5. 01 k W·h,负载累计耗电量为4. 71 k W·h,所选试验条件下优化配置满足牵引装置运行要求。     

独活寄生汤加减配合牵引推拿治疗 腰椎间盘突出症临床观察

〔摘要〕目的观察独活寄生汤加减配合牵引推拿治疗腰椎间盘突出症的临床疗效〔方法将确诊为腰椎间盘 突出症的患者126例,随机分为治疗组和对照组各63例、治疗组采用独活寄生汤加减配合牵引推拿治疗,对照组单 纯采用牵引推拿治疗〔14 d为1个疗程〔观察比较两组患者治疗前后疼痛程度(VAS评分)的变化及疗效〔结果治 疗组总有效率为92.1 %,对照组总有效率79.40Ic,两组差异有统计学意义(P<0.05 )治疗组与对照组组内治疗前后疼 痛程度VAS评分比较差异有统计学意义(P<0.01),组间差值比较,差异有统计学意义}P<0.05)〔结论独活寄生汤加 减配合牵引推拿治疗腰椎间盘突出症效果确切.能明显缓解患者腰腿痛症状.提高生活质量.值得推)‘一运用、     

牵引电磁铁的驱动电源设计

为了解决天车制动器电磁铁的发热问题,讨论了牵引电磁铁的机械特性、分析了供电方式对牵引力的影响。指出对于铁芯移动的电磁铁而言,由于气隙对于牵引力的影响,恒定电源供电存在较大的弊病。在此基础上提出了一种基于多谐振荡器的变电压供电电源,高电压产生初始牵引力,铁芯吸合后降低电压保持位置,在不影响拖动性能的基础上,减小了工作损耗,平均无故障时间明显增长。说明铁芯移动的电磁铁采用变电压供电是可行的。     

半挂汽车列车鞍座参数匹配及行驶特性分析

为分析具有侧向自由度的半挂汽车列车行驶特性,建立了包含车身侧倾和转向系刚度的车辆模型,对车辆在典型工况下的运行状态进行仿真分析;并对模型中的牵引鞍座参数进行调试和匹配,分析这些参数变化对系统稳定性的影响,以期为车辆系统设计提供参考依据.研究结果表明,行驶状况和牵引鞍座参数的变化,可能造成车身侧倾、两车存在夹角等,应通过参数灵敏度进行分析判断;仿真结果说明所建模型适用于分析车辆行驶特性.     

与中央制动器制成一体的汽车滑行节能装置研究

研制了一种与驻车制动器制成一体的滑行节能装置,并进行了实车试验,结果表明,该自动滑行器既能使汽车在高速时自动滑行省油,又能在低速时利用发动机的制动牵阻作用保障汽车的安全性能。     

基于ANSYS的农机单轮测试装置结构设计与优化

设计一套测试轮胎型号介于6.00-12与9.5-20之间的单轮牵引性能测试试验装置。对比分析了滑轨-内外框架式与平行四连杆-内外框架式2种框架结构的优缺点,确定使用前者作为装置主体,液压马达作为驱动轮胎动力源。针对在试验过程中由于地面不平整而导致传感器测力方向不稳定的问题,设计了内外框架的整体结构:测力传感器布置于内外框架间,使用预紧弹簧使两端球铰式拉压传感器始终受到拉力。利用Pro/E软件建立了装置框架三维模型,同时建立了计算外框架最大应力的数学计算模型并进行了计算。利用有限元分析软件ANSYS对其内外框架进行应力应变仿真,最大应力结果与理论计算结果相近,并在此基础上进行了结构强度分析和优化。结果表明,优化后内外框架在保证框架总体重量最小的基础上应力应变明显减小,达到使用刚度、强度。针对内外框架试验时的振动特性进行了模态分析和预测,仿真后分别得到了内外框架前四阶的固有振动频率。